Animation of our Milky Way galaxy based on a detailed supercomputer simulation. The movie zooms in and out of the galaxy, showing what it would look like in visible wavelengths. Blue regions are young star clusters which have blown away the gas and dust out of which they formed. Red regions are obscured by large amounts of dust.

Simulated view of the formation of our Milky Way galaxy. The simulation begins moments after the birth of the universe 13.8 billion years ago and ends with our mature, present-day Milky Way galaxy. Pockets of matter are seen growing in size, and merging with each other, due to the force of gravity. The clock in the corner denotes the passage of time using a convention astronomers refer to as redshift, or "z." The universe begins at a z value of 30, while the present-day has a z value of zero.

Andrew Wetzel, Caltech-Carnegie research fellow, talks about using a simulation of our Milky Way galaxy to predict the numbers of dwarf galaxies surrounding it. He describes the "aha" moment of realizing that they could correctly predict dwarf galaxies in numbers similar to what is observed.

Phil Hopkins, associate professor of theoretical astrophysics at Caltech, describes the most realistic, sophisticated simulation of our Milky Way galaxy to date—a tool astronomers use to trace how the galaxy developed.

Images

Simulated View of Milky Way GalaxySimulated view of our Milky Way galaxy, seen from a nearly face-on angle. This image was created by simulating the formation of our galaxy using a supercomputer, which, in this case, consisted of 2,000 computers linked together.

Simulating Our Galaxy and Its Little CompanionsIn a new simulation of the formation of our Milky Way galaxy, astronomers were able to, for the first time, correctly predict the number of dwarf galaxies observed today. Dwarf galaxies are small galaxies that swarm around the outside of the Milky Way. Prior simulations found thousands of dwarf galaxies—far more than the 30 or so observed so far. This image from the new simulation shows our galaxy with the correct number of dwarf galaxies. The streak is a tidal tail from a torn-apart dwarf galaxy.